What best practices should be followed when handling form data in PHP to ensure session variables are correctly populated?

When handling form data in PHP, it is important to sanitize and validate the input before using it to populate session variables. This helps prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. Additionally, make sure to properly initialize session variables and set them based on the sanitized form data. 

// Sanitize and validate form data
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);
$password = filter_var($_POST['password'], FILTER_SANITIZE_STRING);

// Check if form data is valid
if (!empty($username) && !empty($password)) {
    // Initialize session
    session_start();
    
    // Set session variables
    $_SESSION['username'] = $username;
    $_SESSION['password'] = $password;
}

Keywords

form data PHP session variables handling best practices

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